Whereas projections for the regional labour demand have been developed by theregional network of the IAB for a while, comparable regional differentiated projectionof the labour supply are available for West and East Germany each, but not on adeeper regional level up to now. The reasons are both data problems and capacityrestrictions. Therefore, this article discusses, whether it might be possible using asimplified approach to estimate the potential labour force for single German Federal“Länder”. Our approach was tested for the Saarland.A typical forecast of the labour supply is based upon two elements: a projection ofthe population and an estimate of future activity rates. For the population projectionof the Saarland the „11th coordinated population projection“, calculated by the GermanFederal Statistical Offices and the Statistical Offices of the Länder, was taken.The second element, the estimation and projection of labour participation rates inthe Saarland, was in the focus of this article. These estimations were based on projections,which were calculated by the IAB for West Germany. Due to the concept ofthe potential labour supply, there should be no substantial difference in (potential)activity rates of the Saarland and West Germany, if unemployment were on thesame level – all other influences kept constant. Our estimations show that there willbe in fact no significant difference in potential labour participation, if the influence ofthe unemployment rate is taken into account. For that reason, we conclude that it ispossible to use those potential activity rates, which are projected for West Germany,for the Saarland as well.Based on the population projection of the Statistical Offices for the Saarland and theIAB-forecast of the labour participation for West Germany, the labour force potentialof the Saarland will moderately decline up to 2020. But this process acceleratesenormously. Especially from 2020 onwards it gains on strength, driven by low birthrates and an ageing baby-boom generation. The labour force potential of the Saarlandwill shrink even a little more than the West German is assumed to.Demography will also shift the age structure of the labour force potential in the Saarland.Whereas the 40- to 49-year-olds is the strongest age-group today, in 2020 thenumerically biggest age group will be the 50- to 59-year-olds.All in all, the demographic trend is the most important influencing factor on laboursupply. The analyses show that neither high net migration flows nor increasing femalelabour participation rates respectively an extension of the working life (old-agepensions with 67) will be able to stop the trend.